Dynamic Spectrum Access (DSA) is a spectrum sharing paradigm that allows secondary users to access unused spectrum in a frequency band licensed to primary users. A typical secondary user may utilize a spectrum harvester to scan a frequency band to look for unused spectrum. The secondary user may then use the harvested (unused) spectrum opportunistically.
It is noted that while a number of spectrum harvesting techniques are currently available, the currently available spectrum harvesting techniques tend to have difficulties finding frequency hopping emitters because frequency hopping emitters can only be found if their transmissions coincide with the scanning cycle of the spectrum harvesting technique used. In addition, some radio frequency emitters (fixed frequency or frequency hopped) may not be detectable due to shadowing, fading, noise, and various other factors.